People can be unaware of important sounds while they're listening to headphones. The drawback of an immersive headphone experience is the possibility of not being alerted to external sounds. This issue becomes especially problematic during the use of noise-cancelling headphones and high volume listening.
Common methods of environmental awareness for headphone users are to have a headphone over only one ear, to play audio at a low volume, or to use headphones that don't completely surround a user's ear.
Currently, the most applicable solution to this issue is presented in some phone apps. These phone apps interrupt audio transmitted to headphones when external sound exceeds a threshold. However, these apps are not portable and cannot be used in other audio devices such as laptops, stereo receivers, and MP3 players.
U.S. Pat. No. 4,250,499 issued to Kienzle proposes an alarm device that detects when sound is above a threshold and either disconnects earphones from an audio source and then connects the microphone to the earphones, or generates an output notification signal that connects to earphones. It proposes using a potentiometer to adjust the detection level threshold. U.S. Pat. No. 4,827,458 issued to D'Alayer de Costemore D'Arc proposes to alert the headphone user only for sounds that could possibly signal an abnormal event. External sound that is too brief or gradual would not be considered indicative of an abnormal event and the user would not be alerted. The user is either alerted by the audio signal transmission being attenuated or cutoff, or by an alert sound that is superimposed on the audio signal. A potentiometer is used to set the sensitivity of the system to sound surges and the characteristics resulting in an alert. It proposes the device to be small enough to easily incorporate into the listening device or audio source itself. It also proposes for the microphone to be mounted to the listening device or audio source. U.S. Pat. No. 8,194,865 issued to Goldstein et al. proposes a system that recognizes sound signatures and uses localization to identify pre-determined sounds of interest to the user. It proposes alerting the user to predetermined environmental sounds by different means including amplifying the environmental sound of interest, attenuating interfering environmental sound, reciting a predetermined identifying label by means of a text-to-speech converter, rendering a sound pre-associated with the environmental sound, reciting localization information, and discontinuing playback of audio.
Although these references propose systems for providing notification of external events to headphone users, they do not provide a feature to automatically adjust the sound interrupting threshold based on the ambient sound level. These systems only propose manual sound interrupting threshold adjustments that require the user to gauge the ambient sound level. The limitations of these existing implementations and proposals necessitates a device that features both an option to automatically adjust the sound interrupting threshold based on ambient sound and compatibility with any audio source.